Phenolic corrosion inhibitors



United States Patent 3,320,163 PHENOLIC CORROSION INHIBITORS Andrew D.Abbott, Greenbrae, and Warren Lowe, Berkeley, Calif, assignors toChevron Research Company, San Francisco, Calif., a corporation ofDelaware No Drawing. Filed (let. 8, 1965, Ser. No. 494,259 4 Claims.(Cl. 252-481) This invention concerns novel improved ashless oxidationinhibitors and wear reducing agents comprising highly sulfurizedalkylphenols.

Alloy bearings containing such metals as cadmium, silver, copper, nickeland lead find wide application in a variety of internal combustion orsteam turbine engines. These bearings are particularly susceptible towear under the ever-increasing bearing loads, speeds and temperatures ofoperation. Moreover, the lubricating oils which are used to protect thebearings are themselves subjected to deterioration, forming sludge, thedegradation products enhancing wear and interfering with the efiicientoperation of the moving parts.

It has now been found that the effectiveness as oxidation inhibitors andantiwear agents of alkylphenols having disulfide linkages can be greatlyenhanced by incorporating into the alkyl disulfide from 1 to 10 percentby weight of sulfur based on the alkylphenol disulfide by heating thealkylphenol disulfide with sulfur at a temperature in the range of about225 to about 400 F, preferably 280 to 330 F.

The alkylphenol having disulfide linkages will for the most part havethe following formula:

OH OH OH I S2 82L R n R wherein R is an alkyl group of from 8 to 20carbon atoms, more usually of from 10 to 16 carbon atoms, and n is aninteger of 0 to 10, generally not greater than 6. The above compositionbecomes bis(alkylphenol) disulfide when n is 0.

This composition is prepared by reacting in a 2:1 mole ratio the desiredalkylphenol with sulfur monochloride.

Since the stoichiometry is such that only the bis-disulfide should beformed, evidently if products having more than 2 alkylphenols areformed, some of the alkylphenol remains unreacted. The conditionsaccording to this invention under which the disulfide alkylphenols arereacted with the sulfur are such that the unreacted alkylphenol will notreact with the sulfur, but remain an inert ingredient, not becomingincorporated with the disulfide or the additional sulfur. The presentinvention, therefore, is not concerned with sulfurizing the unreactedalkylphenols.

The bis-disulfide is prepared by dissolving in an inert medium, e.g., ahydrocarbon medium, about 2 moles of alkylphenol with 1 mole of sulfurmonochloride (S CI and then heating the reaction mixture in the range ofabout 120 to 200 F, while sweeping out the HCl which is formed. Theresulting product may then be purified by any convenient means.

According to this invention, from about 1 to 10 weight percent, moreusually from about 1 to weight percent of sulfur is added to the abovereaction mixture, based on the weight percent of the alkylphenoldisulfide. (Since all of the alkylphenol has not reactedgenerally thiswill be less than 25 weight percent of the total alkylphenol chargedtheassumption can be reasonably made that 75 weight percent of the originalalkylphenol charged is present as disulfide and the desired amount ofsulfur added accordingly. Minor variations do not significantly affectthe results obtained by the addition of the sulfur; unre acted) sulfurcan be removed by filtration or centrifugation.

The reaction is preferably carried out in an inert medium, e.g., aninert hydrocarbon solvent, wherein the diluent may be from about 5 to 50weight percent, more usually from about 1 0 to 30 weight percent of thetotal composition.

The temperature for the reaction is generally in the range of 225 to 400R, usually 280 to 330 F. The time for the reaction will usually notexceed 24 hours, generally being in the range of 2 to 12 hours; Thereaction will usually be stopped when it appears that all the sulfurwhich is going to be incorporated, has been incorporated.

The manner in which the sulfur is incorporated into the alkylphenoldisulfide is not known, but the sulfur is apparently present in somecombined form, rather than just solubilized free sulfur.

The following examples are offered by way of illustration and not by wayof limitation.

EXAMPLE A.REACTION OF ALKYLPHENOL WITH SULFUR MONOCHLORIDE Into a vesselwas charged 8,580 parts of largely dodecylphenol (primarilypara-substituted), 3,150 parts of a Mid-Continent 'SAE 100 neutral oil,a small amount of a foam inhibitor and the mixture agitated while addingportionwise 1,930 parts of sulfur monochloride. The temperature of thereaction mixture was maintained at about to F. during .the addition.When the addition was complete, the temperature was raised to to F and aslow stream of nitrogen passed through the reaction mixture. A partialvacuum was applied to the system. The reaction mixture was then washedwith water and the organic layer separated from the aqueous layer.

Example 1 A. Into a reaction vessel was introduced 267 g. ofdodecylphenol disulfide prepared as described above and 8.54 g. ofsulfur, the mixture being heated at 300 F. for 12 hours, allowed to cooland filtered.

At the end of this time, the sedimentation number was 0.006 volumepercent; that is, the amount of sulfur removed by centrifugation.

B. The above procedure was repeated using the same amount ofdodecylphenol disulfide, but 4.27 g. of sulfur was added.

Example 2 Into a reaction vessel was introduced 1,335 g. ofdodecylphenol disulfide (percent S=9.7) prepared as described above,heated with stirring to 300 F. and 211.4 g. of sulfur added. Stirringand heating were maintained for 12 hours after which time the reactionmixture was filtered and isolated.

The compositions of this invention can be used with a variety of oils,that is, fluids of lubricating viscosity. Base oils include suchnaturally occurring oils as naphthenic base, paraflin base, asphalticbase and mixed base lubricating oils. Other hydrocarbon lubricantsinclude lubricating oils derived from coal products, synthetic oils suchas polymers of propylene, butylene, etc., aromatic hydrocarbons, etc.Other illustrative oils are the esters of organic and inorganic acids,e.g., c-arboxylates such as octyl azelate, octyl sebacate, etc. andsilicates and phosphates. Also alkylene oxides and polymers thereof maybe used.

The above base oils may be used individually or in combination, whenevermiscible or made so by the use of mutual solvents.

The additives of this invention will generally be present in lubricatingoils in amounts of from about 0.5 to- 20 weight percent of the totalcomposition, more usually in amounts of from about 1 to 4 weight percentof the total composition.

In order to demonstrate the enhanced effectiveness of the compositionsof this invention as additives of lubricating oil, a number of testswere carried out to determine their effectiveness in preventing wear andoxidative deterioration. The following table demonstrates the resultsobtained in the Falex Extreme Pressure Wear and Shear Test. Thecomposition used was 21 Mid-Continent SAE 30 oil containing 2.4 weightpercent of a commercial ashless detergent (a polyisobutenyl succinimideof tetraethylene pentamine) and 0.08 weight percent of terephthalic acid(corrosion inhibitor). To this reference oil was added 1.5 weightpercent of a dodecylphenol disulfide prepared as described in Example Aas a standard and three other samples with varying amounts of sulfurcombined with the dodecylphenol disulfide prepared as described inExamples 1 and 2. The following table indicates the results:

TAB LE I Shear, lbs. to

Mole Ratio of bis(dodecyl- Failure The mole ratio is based on thepresumption that all of the dodecylphenol charged reacted to form thebis(dodecylphenol) disulfide, the bis(dodecylphenol) disulfide neverhaving been isolated but reacted directly with the indicated amount ofsulfur.

An oxidation test was carried out to determine the amount of oxygenabsorbed under the test conditions, indicating the oils usefulness in acompounded engine oil. A 25 g. sample was prepared from 480 neutral oilcontaining 5 weight percent of a commercial ashless detergent(polyisobuteuyl alkenyl succinimide of tetraethylene pentamine), 0.1weight percent of terephthalic acid and 2.2 weight percent of thebis(dodecylphenol) disulfide with and without additional combinedsulfur. To the 25 g. sample was added 0.2 cc. of a solution having 3,160p.p.m. of copper, 2,670 p.p.m. of iron, 1 60 p.p.m. of manganese, 36,700p.p.m. of lead and 1,630 p.p.m. of tin as their naphthenates, providinga distribution of metals which would be expected to be found in usedcrankcase oils after an L-4 Chevrolet Engine Test. The oil solution tobe tested is then maintained at 340 F. for a period of 6.5 hours and thetotal oxygen observed.

Also carried out was a copper corrosion test, using /2" x 3 copperstrips polished with steel wool. In this test, a ml. sample is placed ina test tube and heated to 300 F. The freshly polished strip is thenimmersed in this sample for 5 minutes, removed from the test solution,immersed in an isooctane solution until cool, and then rinsed withisooctane. Discoloration of the copper is reported in comparison to theASTM D 130 copper strip corrosion standards. The following tableindicates the results obtained with varying amounts of sulfur.

9.9 total weight percent sulfur was tested in a high-load Chevrolet L-4Engine Test. The usual L-4 test conditions are described in an articlepublished by the SAE, 573B, delivered at the National Farm, Constructionand Industrial Machinery Meeting, Sept. 10-13, 1962, by Christiansen andBrown.

Under the high-load conditions, a load of B.H.P. rather than 30 B.H.P.is used and no tetraethyl lead is used in the fuel. Rather, clearalkyl-ate is used. Also, the test period is extended to 56 hours from 36hours.

The sample used contained 2.2 weight percent of additive, 0.1 percent ofterephthalic acid and 5 weight percent of calciumdi(polypropylenephenyl) dithiophosphate (polypropylene of from 12 to 15carbon atoms) in a 480 neutral oil. At 56 hours the unsulfurizedbis(dodecylphenyl) disulfide had an increase in viscosity of the subjectoil at 100 F. of greater than 102 percent, while the sulfurizeddisulfide, had an increase of the subject oil of only 61 percent.

Not only do the compositions of this invention act as corrosioninhibitors, but they also reduce the sludge formed in the oil whichresults in undesirable thickening.

As will be evident to those skilled in the art, various modifications onthis invention can be made or followed, in the light of the foregoingdisclosure and discussion, without departing from the spirit or scope ofthe disclosure or from the scope of the following claims.

We claim:

1. A composition of matter which comprises the reaction product of acompound according to the formula:

2. A composition of matter which comprises the reaction product of acompound of the formula:

OH OH OH R R n R wherein R is an alkyl group of from 8 to 20 carbonatoms, n is a cardinal number not greater than 10 and primarily 0, withsulfur in from 1 to 10 weight percent based on TABLE II Wt. percent Sadded (theoretical dodecyl disulfide) 1. 1 2.2 4.4. Total wt. percent ofS 6.6 7. 74 8.62, 8.35 10.5. Copper strip test Bad flake 3A 3B, 4B someflake 3B some flake. Oxidation test:

Hrs. to absorb 1000 m1. O 1.5-. 1.7 2.2 3.1. Total 0 absorbed in 6.5hrs., m1 4,000 3, 800 2,840 2,480.

1 The bis(dodecylphenol) disulfide was prepared as described in ExampleA; the additional sulfur was incorporated as described in Example 1,except that the reaction time was only 6.5 hours.

It is evident from the above results that by combining excess sulfur,great enhancement of oxidation inhibition is obtained. Furthermore, wearis greatly reduced. At the same time, the excess sulfur does not makethe oils excessively corrosive to copper.

To further demonstrate the effectiveness of the compositions of thisinvention as lubricating oil additives, a composition prepared asdescribed in Example 1 having the weight of said compound at atemperature in the range of 200 to 400 F. and in the presence of from 5to 50 weight percent of the total composition of an inert hydrocarbonsolvent.

3. A composition according to claim 2, wherein R is of from 10 to 16carbon atoms, and sulfur is added in an amount of from 1 to 5 weightpercent of said compound.

4. A lubricating composition comprising an oil of lubri-' 5 6 eatingviscosity and from 0.5 to 20 weight percent of 3. 2,346,826 4/1944 Cooket a1. 25248.2 composition according to claim 1. 3,057,926 1 0/1962Cofiield 260'6 0 8 3,250,712 5/ 1966 Coffield 25248.2

References Cited by the Examiner UNITED STATES PATENTS 2,230,542 2/ 1941Meinert et a1 260608 2,237,627 4/ 1941 Olin 260608 5 DANIEL E. WYMAN,Primary Examiner.

L. G. XIARHOS, Assistant Examiner.

1. A COMPOSITION OF MATTER WHICH COMPRISES THE REACTION PRODUCT OF ACOMPOUND ACCORDING TO THE FORMULA:
 4. A LUBRICATING COMPOSITIONCOMPRISING AN OIL OF LUBRICATING VISCOSITY AND FROM 0.5 TO 20 WEIGHTPERCENT OF A COMPOSITION ACCORDING TO CLAIM 1.